Constructing a confidence interval for a regression coefficient

Hi all, this is my first time posting here but I've been reading through the forums and it's been a great help so far. So thanks to everyone for their great help in the past

My question is this. I've been given the following regression:

weight = -99.41 + 3.94(height); R(squared) = 0.81; SER = 10.2

I'm first asked to find what the regression's prediction for the increase in a man's weight if he hits a growth spurt of 1.5 inches. Easy enough, that's 3.94*1.5=5.91.

Then it asks me to construct a 99% confidence interval for the person's weight gain. So this is a confidence interval for a particular regression coefficient, specifically the B1 (or 3.94) in the equation. But I'm only aware of doing this when knowing the Standard Error of the coefficient, which is not provided here. Does anyone know what I need to do to proceed? Is there a way to do it?